Replaced signal handlers with signalfd + pool

dwmblocks.c

@@ -6,6 +6,8 @@
 #include <signal.h>
 #include <errno.h>
 #include <X11/Xlib.h>
+#include <sys/signalfd.h>
+#include <poll.h>
 #define LENGTH(X) (sizeof(X) / sizeof (X[0]))
 #define CMDLENGTH		50
 
@@ -15,16 +17,13 @@ typedef struct {
 	unsigned int interval;
 	unsigned int signal;
 } Block;
-void sighandler(int num);
-void buttonhandler(int sig, siginfo_t *si, void *ucontext);
+void sighandler();
+void buttonhandler(int ssi_int);
 void replace(char *str, char old, char new);
 void remove_all(char *str, char to_remove);
 void getcmds(int time);
-#ifndef __OpenBSD__
 void getsigcmds(int signal);
 void setupsignals();
-void sighandler(int signum);
-#endif
 int getstatus(char *str, char *last);
 void setroot();
 void statusloop();
@@ -39,6 +38,8 @@ static Window root;
 static char statusbar[LENGTH(blocks)][CMDLENGTH] = {0};
 static char statusstr[2][256];
 static int statusContinue = 1;
+static int signalFD;
+static int timerInterval = -1;
 static void (*writestatus) () = setroot;
 
 void replace(char *str, char old, char new)
@@ -128,7 +129,6 @@ void getcmds(int time)
 	}
 }
 
-#ifndef __OpenBSD__
 void getsigcmds(int signal)
 {
 	const Block *current;
@@ -143,22 +143,20 @@ void getsigcmds(int signal)
 
 void setupsignals()
 {
-	struct sigaction sa;
-
-	for(int i = SIGRTMIN; i <= SIGRTMAX; i++)
-		signal(i, SIG_IGN);
-
-	for(int i = 0; i < LENGTH(blocks); i++)
-	{
+	sigset_t signals;
+	sigemptyset(&signals);
+	sigaddset(&signals, SIGALRM); // Timer events
+	sigaddset(&signals, SIGUSR1); // Button events
+	// All signals assigned to blocks
+	for (size_t i = 0; i < LENGTH(blocks); i++)
 		if (blocks[i].signal > 0)
-		{
-			signal(SIGRTMIN+blocks[i].signal, sighandler);
-			sigaddset(&sa.sa_mask, SIGRTMIN+blocks[i].signal);
-		}
-	}
-	sa.sa_sigaction = buttonhandler;
-	sa.sa_flags = SA_SIGINFO;
-	sigaction(SIGUSR1, &sa, NULL);
+			sigaddset(&signals, SIGRTMIN + blocks[i].signal);
+	// Create signal file descriptor for pooling
+	signalFD = signalfd(-1, &signals, 0);
+	// Block all real-time signals
+	for (int i = SIGRTMIN; i <= SIGRTMAX; i++) sigaddset(&signals, i);
+	sigprocmask(SIG_BLOCK, &signals, NULL);
+	// Do not transform children into zombies
 	struct sigaction sigchld_action = {
   		.sa_handler = SIG_DFL,
   		.sa_flags = SA_NOCLDWAIT
@@ -166,7 +164,6 @@ void setupsignals()
 	sigaction(SIGCHLD, &sigchld_action, NULL);
 
 }
-#endif
 
 int getstatus(char *str, char *last)
 {
@@ -206,52 +203,57 @@ void pstdout()
 
 void statusloop()
 {
-#ifndef __OpenBSD__
 	setupsignals();
-#endif
     // first figure out the default wait interval by finding the
     // greatest common denominator of the intervals
-    unsigned int interval = -1;
     for(int i = 0; i < LENGTH(blocks); i++){
         if(blocks[i].interval){
-            interval = gcd(blocks[i].interval, interval);
+            timerInterval = gcd(blocks[i].interval, timerInterval);
         }
     }
-	unsigned int i = 0;
-    int interrupted = 0;
-    const struct timespec sleeptime = {interval, 0};
-    struct timespec tosleep = sleeptime;
-	getcmds(-1);
-	while(statusContinue)
-	{
-        // sleep for tosleep (should be a sleeptime of interval seconds) and put what was left if interrupted back into tosleep
-        interrupted = nanosleep(&tosleep, &tosleep);
-        // if interrupted then just go sleep again for the remaining time
-        if(interrupted == -1){
-            continue;
-        }
-        // if not interrupted then do the calling and writing
-        getcmds(i);
-        writestatus();
-        // then increment since its actually been a second (plus the time it took the commands to run)
-        i += interval;
-        // set the time to sleep back to the sleeptime of 1s
-        tosleep = sleeptime;
-	}
+    getcmds(-1);     // Fist time run all commands
+    raise(SIGALRM);  // Schedule first timer event
+    int ret;
+    struct pollfd pfd[] = {{.fd = signalFD, .events = POLLIN}};
+    while (statusContinue) {
+        // Wait for new signal
+        ret = poll(pfd, sizeof(pfd) / sizeof(pfd[0]), -1);
+        if (ret < 0 || !(pfd[0].revents & POLLIN)) break;
+        sighandler(); // Handle signal
+    }
 }
 
-#ifndef __OpenBSD__
-void sighandler(int signum)
+void sighandler()
 {
-	getsigcmds(signum-SIGRTMIN);
+	static int time = 0;
+	struct signalfd_siginfo si;
+	int ret = read(signalFD, &si, sizeof(si));
+	if (ret < 0) return;
+	int signal = si.ssi_signo;
+	switch (signal) {
+		case SIGALRM:
+			// Execute blocks and schedule the next timer event
+			getcmds(time);
+			alarm(timerInterval);
+			time += timerInterval;
+			break;
+		case SIGUSR1:
+			// Handle buttons
+			buttonhandler(si.ssi_int);
+			return;
+		default:
+			// Execute the block that has the given signal
+			getsigcmds(signal - SIGRTMIN);
+			break;
+	}
 	writestatus();
 }
 
-void buttonhandler(int sig, siginfo_t *si, void *ucontext)
+void buttonhandler(int ssi_int)
 {
-	char button[2] = {'0' + si->si_value.sival_int & 0xff, '\0'};
+	char button[2] = {'0' + ssi_int & 0xff, '\0'};
 	pid_t process_id = getpid();
-	sig = si->si_value.sival_int >> 8;
+	int sig = ssi_int >> 8;
 	if (fork() == 0)
 	{
 		const Block *current;
@@ -271,12 +273,10 @@ void buttonhandler(int sig, siginfo_t *si, void *ucontext)
 	}
 }
 
-#endif
 
 void termhandler(int signum)
 {
 	statusContinue = 0;
-	exit(0);
 }
 
 int main(int argc, char** argv)
@@ -291,4 +291,5 @@ int main(int argc, char** argv)
 	signal(SIGTERM, termhandler);
 	signal(SIGINT, termhandler);
 	statusloop();
+	close(signalFD);
 }